Tylo capture at jool to not use much of Delta V

[EdwardB3020]

I've watched Matt Lowne do several Tylo encounters to get captured around Jool, I want to know how to do that. I only managed to get it once and it was a pain. 

Can someone make a text or video tutorial please? 

[KerikBalm]

Its fairly easy to use a single Tylo gravity assist to get captured around Jool in a single pass. Several passes would be used if you want to enter into orbit around one of the moons using less dV

[Bill Phil]

Basically you have to use higher patched conic numbers and play around with maneuver nodes. Capture at Jool is easy enough, but playing around with gravity assists to lower moon capture delta-v can be very tricky.

[Aeroboi]

 Firstly you need to set the patched conic draw mode to a high number in the game settings as Bill Phil suggested. Each number represents how many times patched conics recalculates orbits during SOI changes and then draws it. So setting it to a high number allows you to see several SOI changes in advance whether your going to meet with Tylo or any other planetary body for that matter.

The trick is to enter Jool SOI when Tylo is at the right spot in its orbit around Jool. Since this isn't always the case you want to change the time of Jool encounter by increasing or decreasing that time. Make a maneuver node halfway out to Jool then switch to Jool in map mode and play with the maneuver node. You want to make sure the expected orbit is close to Tylo's altitude around Jool while increasing/decreasing the encounter to Jool until it matches with a Tylo encounter.

Note that you want to make sure that you slingshot around Tylo in a retrograde direction relative to jool so make sure that encounter allows a retrograde slingshot, or at least radially out to kill your velocity.

Once there fine tune the encounter with Tylo so that you kill most of the energy possible. Then create a encounter again at Jool apoapsis and do another gravity assist. From there on it doesn't necessarily have to be Tylo of course, Laythe will do fine also.

[purpleivan]

Here's one I made earlier... for the Terminus challenge a few weeks ago.

 

[Tyko]

This is actually a really good article explaining how gravity assists work

https://medium.com/the-space-perspective/gravity-assists-explained-simply-how-the-voyager-spacecrafts-escaped-the-solar-system-d8aaa4a9273c

 

[mystifeid]

4 hours ago, Aeroboi said:

Note that you want to make sure that you slingshot around Tylo in a retrograde direction relative to jool so make sure that encounter allows a retrograde slingshot, or at least radially out to kill your velocity.

Retrograde slingshot? Radial out?

I might be misunderstanding you but I would call @purpleivan's example prograde, radial in.

Here is another example in the same vein - 130m/s capture plotted from a maneuver node half-way to Jool. I happen to have a save-game at this point and if I move the trajectory to the other side of Tylo, I get a nice assist out of Jool's SOI. Maybe if Tylo is on the other side of Jool, retrograde radial in might work but I'd imagine it would always be best if Tylo is not far from where it is now - on the trailing side of Jool's orbit.

[Aeroboi]

@mystifeid lol, I litteraly thought upside down if you get what I'm saying. Sorry   

[Gordon Fecyk]

Something I haven't seen in the answers yet, is to try to get your Tylo encounter close to or at Jool periapsis, so you get the most benefit from the Tylo encounter. This is just like doing a normal capture burn at Jool periapsis to take the most advantage of the Oberth effect. This will mean adjusting your arrival time at Jool to match when Tylo would be in the right spot.

I can't take screen shots right now, but I believe, assuming you're on the same orbital plane as Jool's orbit with the sun, you can use prograde / retrograde on your manoeuvre node to adjust your arrival time, and then radial in / out to adjust your arrival position. It helps to pick Tylo as your target rather than Jool, once you have your orbit plane lined up with Jool itself. Then you want to pass in 'front' of or 'inside' of Tylo to slow down, as close to Tylo's surface as you dare.

If you can't quite get the timing right, try getting an encounter with Laythe instead. You won't be able to get as close to Laythe because of its atmosphere, but it moves faster than Tylo does which can make up the difference.

And sometimes, if you timed it well, you can pass in front of Vall right after your pass in front of Tylo and get an additional assist to slow down further.

[Atkara]

I'll try to explain, although chances are I'll confuse you more than help you.

With your initial ejection burn you ensured a Jool encounter. Now that you've exited Kerbin's SOI, you need to adjust your trajectory in such a way, so that:

1. You get a prograde Jool flyby, while crossing Tylo's orbit. That's the easiest part, as it's a matter of pro/retrograde and in most cases normal/antinormal input.

2. Tylo is where you cross it's orbit at. 50% of the time, Tylo is anywhere but where you want it to be. So you make it be there. I usually start with radial out and retrograde input, followed by a process of trial and error with radial in/out and pro/retrograde, till the closest approach with Tylo is where I want it to be.

3. Your encounter with Tylo results in a Jool capture. You need to get behind it so that it's gravity reduces your velocity, instead of increasing it. Assuming you succeeded in step 2, it's usually a matter of pro/retrograde input.

4. The resulting Jool capture won't be at a weird orbital plane. This normally belongs to step 3, but I didn't want to clutter it. This is achieved by adding enough normal/antinormal input to get you to an orbital plane that suits your needs. If your final destination is Bop or Pol, you adjust for that. If you're headed to one of the inner moons, you settle for a "flat" orbital plane.

The hardest part is that all of these wonders are to be achieved on a single maneuver, halfway between Kerbin and Jool. A tall order and at the same time, doable.

 

[Eriksonn]

The most important thing for me is to enable the setting that shows closest approach at all times, this will make it easy to see where tylo is and where you want it when you arrive. And if it is wrong you mess with prograde/radial until the closest approach markers come closer to eachother.

[mystifeid]

Once you have achieved an intercept, KSP's map mode shows two positions for the body - current position and position at intercept. Are you clicking on the current position and selecting "Focus View"? This allows you to zoom in and see a duplicate view of the intercept in intimate detail. This is especially helpful when you are playing with a maneuver node a long way from the intercept.

[Gordon Fecyk]

I've never attempted a proper low delta-v Jool mission before, but just yesterday I started experimenting with a probe launched at the start of a new sandbox save. If I get something to orbit quickly enough, I can do one of those fancy Eve-Kerbin-Jool tours and get a Jool capture via Tylo with about 1500 m/s only. The most expensive burn was the one out to Eve at 1450 m/s or so. Of course it takes six Kerbin years to get there.

I do have captured video of that, but it's very rough and not very cinematic. I'll have to try again.